Cooling device for castings in continuous casting installations for heavy metals or alloys thereof,particularly steel

ABSTRACT

A COOLING DEVICE FOR CASTING IN CONTINUOUS CASTING INSTALLATIONS FOR HEAVY METALS OR ALLOYS THEREOF, PARTICULARLY STEEL, WHICH COMPRISES A COPPER CASTING DIE SERVING AS CONTINUOUS MOLD TO THE INTERIOR OF WHICH A COOLANT IS ADMITTED FOR INDIRECTLY COOLING A CASTING. A COOLING SECTION IS FORMED BY SPRAYING NOZZLES FOLLOWING THE CASTING DIE AND SERVING FOR DIRECTLY SPRAYING THE COOLANT ONTO THE CASTING. THIS COOLING SECTION SUBSTANTIALLY CONSISTS OF AT EAST ONE WATER CHAMBER EQUIDISTANTLY SURROUNDING THE CASTING AND CONNECTED TO AT LEAST ONE ROW OF FLAT JET NOZZLES WHICH ARE FORMED AND ARRANGED IN SUCH A MANNER THAT THEY SPRAY FLAT JETS OF HIGH KINETIC ENERGY ONTO THE SURFACE OF THE CASTING. THESE JETS ARE INTENDED CONTINUOUSLY TO EXTEND AXIALLY ALONG THE ENTIRE LENGTH OF SAID COOLING SECTION AND SUBSTANTIALLY SPACELESS JOIN UP WITH EACH OTHER IN THE AREA OF IMPINGEMENT ON THE SURFACE OF THE CASTING.

March 23, 1971 alc ETAL 3,572,423

COOLING DEVICE FOR CASTINGS IN CONTINUOUS CASTING INSTALLATIONS FOR HEAVY METALS OR ALLOYS THEREOF, PARTICULARLY STEEL File d Sept 25. 1968 SShuets-Shoyt L F IG. 5

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- coomne mavxcn FOR cAs'rmGs IN connuuous CASTING INSTALLATIONS FOR HEAVY METALS ORsALLOYS THEREOF, PARTICULARLY STEEL Filed sept. 25. 1968 3 Sheets-Sheet z By warm; (law/9m,

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March 23, 1971 B ETAL 3,572,423

COOLING DEVICE FOR OASTINGS IN CONTINUOUS CASTING INSTALLATIONS FOR HEAVY METALS OR ALLOYS I THEREOF, PARTICULARLY STEEL Filed Sept. 25. 1968 3 Sheets-Sheet 5 INVENTOR IMAM nlc c doc/fan: (El W" B I 4mm lmnsm United States Patent 3,572,423 COOLING DEVICE FOR CASTINGS IN CONTINU- OUS CASTING INSTALLATIONS FOR HEAVY METALS 0R ALLOYS THEREOF, PARTICULARLY STEEL Klaus Bick, Paderborn, Wolfgang Weinreich, Schloss Neuhaus, and Lothar Harmsen, Paderborn, Germany, assignors to Paderwerk Gebr. Benteler, Schloss Neullaus, Kreis Paderborn, Germany Filed Sept. 25, 1968, Ser. No. 762,481 Claims priority, application Austria, Oct. 2, 1967, 8,926/ 67 Int. Cl. B22d 11/12 US. Cl. 164-283 11 Claims ABSTRACT OF THE DISCLOSURE A cooling device for castings in continuous casting instailations for heavy metals or alloys thereof, particularly steel, which comprises a copper casting die serving as continuous mold to the interior of which a coolant is admitted for indirectly cooling a casting. A cooling section is formed by spraying nozzles following the casting die and serving for directly spraying the coolant onto the casting. This cooling section substantially consists of at least one water chamber equidistantly surrounding the casting and connected to at least one row of flat jet nozzles which are formed and arranged in such a manner that they spray fiat jets of high kinetic energy onto the surface of the casting. These jets are intended continuously to extend axially along the entire length of said cooling section and substantially spaceless join up with each other in the area of impingement on the surface of the casting.

BACKGROUND OF THE INVENTION This invention relates to cooling devices, and more specifically to a device for cooling castings in continuous casting installations for heavy metals or alloys thereof, particularly steel.

For cooling the castings in continuous casting installations for heavy metals or their alloys, particularly steel, it is known to use as continuous mold casting dies of copper which are either worked out of a copper block or assembled from copper plates or copper tubes and to the interior of which a flowing liquid coolant is admitted. According to the diameter or the edge length of the casting these casting dies are about 600 to 1000 mm. long and throughout this length they surround the casting with their inwardly cooled smooth copper surfaces thereby cooling the same indirectly.

In the use of such casting dies the disadvantage became apparent that the casting shell forming during the indirect cooling of the casting owing to contraction of the casting comes off, i.e., recedes from, the copper wall of the casting die, which results in that the lower length portion of the casting die is no longer sufficiently and uniformly cooled. Attempts have been made to make allowance for this contraction of the casting by tapering the casting die so that the inner walls thereof, which form the casting, follow the contraction of thevcasting and thus ensure a better and uniform cooling owing to the tighter contact of the casting shell with the casting die. But since even a casting shell contacting throughout its length the wall of the casting die brings about only relatively poor heat transfer conditions owing to its inherent surface roughness, and since the heat-carrying-oif characteristic is also limited by the fact that it largely depends on the thermal conductivity of the copper material employed, it has become common practice to subject the casting additionally to a direct and more effective cooling with the aid of the ice coolant, particularly water, either already within the copper die or within the area of a cooling section formed by spraying nozzles and provided below the copper die.

The known devices used for this purpose are, however, not satisfactory. Apart from the fact that spraying the casting surface with water through nozzles promotes nonuniform cooling of the casting shell and that non-uniform cooling may result in both breakages and cracks, there is an increased danger, with the cooling water coming forth within the casting die, that the cooling water under too high a pressure gets into the vicinity of the head metal and there causes the steel to boil.

The insufficient direct cooling effect obtained by spraying the surface of the casting with water is substantially due to the fact that the cooling water running off the surface of the casting shell is isolated immediately below the point of impingement of the water, in accordance with the known Leidenfrost-phenomenon, by a steam layer so that it is possible that in this regionup to the following nozzleonly insufficient cooling and, in some cases, even a re-heating of the casting shell may occur from within.

To overcome this disadvantage an older proposal of the inventors, which has not become known in the art, provides a cooling device so constructed that a cooling grate is arranged downstream of the copper casting die shortened in length, which cooling grate consists of narrow guide strips engaging with their free longitudinal edges the casting and arranged in spaced apart relationship so as to form gaps between neighboring guide strips of a width corresponding at least to the thickness of the guide strips, a water chamber surrounding the cooling grate and jet nozzles being connected in the gap regions between adjacent guide strips to the water chamber, said nozzles being designed, arranged and/ or distributed so that within the gaps they direct a high kinetic energy flat jet to the surface of the casting, said flat jet extending throughout the length of the cooling section and being of a breadth substantially narrower than the width of the gaps. It has been found that an optimal and above all a uniform cooling effect can be ensured if the kinetic energy of im pingement of the flat jets amounts at least to about 5 but preferably up to about 20 kp. m./ min. cm. Since the surface of the casting in the closely adjacent gap regions of the cooling grate is directly impinged by high kinetic energy flat jets along the whole length of the cooling section, an isolating steam layer is not allowed to form anywhere along the cooling section, it being particularly achieved that the flat jets can impinge with full power upon the surface of the casting owing to the fact that their breadth is smaller than the Width of the gaps, whereas the water which rebounds from the surface of the casting or which is deflected thereby is forced away by the fiat jets and flows off the side walls of the guide strips by virtue of adhesion.

In all these cases of direct cooling it has been deemed indispensable up to now to support the insufliciently solidified casting shell in the area of the cooling section by guide means in order to prevent the casting shell from being deformed by a bulging of the side walls resulting from the high ferrostatic pressure of the steel the interior of which is still liquid. This applies especially to cases in which a copper casting die shortened in length for the indirect cooling of the casting is used, since in such cases the casting shell is still relatively thin and correspondingly deformable when entering the cooling section following the casting die wherein a coolant is directly sprayed onto the casting.

It has now surprisingly been found that the use of parallel fiat jets of high kinetic energy of impingement which have been employed in the aforementioned proposal for directly spraying a coolant onto the casting and which extend through the entire length of the cooling section, includes the possibility that in this area any mechanical support or guide of the casting shell can be dispensed with. Supposedly, this is primarily due to the fact that the excellent cooling effect of the flat jets results in an accelerated cooling and solidifying of the casting shell and secondly, because the high kinetic energy of impingement of the flat jets neighboring in the vertical exert, as it is, an individual supporting effect on the casting shell.

SUMMARY OF THE INVENTION It is therefore the object of the present invention to provide a cooling system wherein any mechanical support or guide to the casting shell can be dispensed with.

To attain this object, the present invention provides a cooling device for castings in continuous casting installations for heavy metals or alloys thereof, particularly steel, which comprises a copper casting die serving as continuous mold to the interior of which a coolant is admitted for indirectly cooling a casting; a cooling section located downstream of the casting die and formed by at least one row of flat jet nozzles equidistantly surrounding the casting for directly spraying the coolant in the form of flat jets of high kinetic energy onto the surface of the casting, said jets continuously extending axially along the entire length of said cooling section and, neighboring in the circumferential direction of the casting, substantially spaceless joining up with each other in the area of impingement on the surface of the casting, and at least one water chamber communicating with said nozzles.

Apart from the simplification in the construction of the cooling section for directly spraying the coolant onto the casting it is a further substantial advantage of the present invention that, owing to the elimination of the guide means or guide strips, which were deemed indispensable up to now, the flat jets can directly follow up each other in the area of their impingement thereby ensuring a far more intensive and, above all, absolutely uniform cooling of the surface of the casting or the casting shell, which has not been attainable with the means hitherto known in the art.

Although the present invention is preferably applied to castings of square cross sections it is naturally also applicable to castings having rectangular or polygonal cross sections. The specific significance of the present invention, particularly in the case of the last-mentioned cross sectional form, is easily inferrable from the fact that, due to purely practical reasons, it is extremely difiicult especially in the case of polygonal cross sections to guide the casting shell satisfactorily in the area of the direct cooling section with the aid of mechanical means, apart from the fact that any mechanical guide means provided in the area of the direct cooling section automatically involve the disadvantage of excluding or at least considerably impairing the uniform impingement of the coolant on the casting shell. This applies particularly to cases where the impingement of the coolant on the casting shell is to be effected in a manner preventing the formation of isolating steam layers. For this purpose, it is specifically advisable to employ several water chambers, preferably one water chamber for each side wall of the casting, each of which can be brought into its exact position with respect to its side wall of the casting.

In special cases in which it is necessary for the sake of structural height to employ not only a casting die shortened in length but also a shortened direct cooling section, it may be advisable to provide an additional mechanical guide for the casting at least at the bottom end of the cooling section which guide suitably comprises roller guide means enclosing the casting on all sides in a manner known per se.

In general it will suffice when said roller guide means provided at the bottom end of the cooling section comprise only one guide roller on each side of the casting, but it goes without saying that several guide rollers in 4 spaced relationship to each other may be arranged, on each side of the casting, if desired.

The additional use of such roller guide means at the bottom end of the cooling section is particularly advisable in cases where the copper casting die and the following cooling section have about the same length, the length of the copper casting die corresponding to about twice the diameter or twice the edge length of the casting, respectively. In such cases the copper casting die, the cooling section consisting of the flat jet nozzles connected to at least one water chamber and the guide roller means defining the cooling section at the lower end thereof are detachably assembled to form an independent unit.

It has been found to be particularly advantageous to provide in the upper region of said cooling section only one row of fiat jet nozzles so inclined in the direction of movement of the casting that said flat jet nozzles at a spray angle of approximately measured in the vertical, create a flat jet continuously extending along the entire length of the cooling section in the area of impingement, the kinetic energy of impingement of the flat jets gradually decreasing towards the lower end of the cooling section, as cooling demands do.

As set forth in the older proposal, it is possible, however, to arrange several flat or polydirectional jet nozzles along the axial length of the cooling section in such a manner that they jointly create a fiat jet coherent in the area of impingement, the length of said flat jet corresponding to the length of the cooling section and its kinetic energy of impingement being reduced towards the lower end of the cooling section.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention will now be described by way of example and with reference to the accompanying drawings in which:

FIG. 1 is a schematic view, partly in longitudinal section, of the upper end of a casting die;

FIG. 2 is a perspective view, partly in section, of a cooling device according to the present invention, and

FIG. 3 is a cross section through a cooling section serving for the direct cooling of a casting, taken on the line IIIIII of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a ladle 1 containing molten steel 2 which flows through an outlet 3 provided in the ladle 1 into a copper casting die 4 into the interior of which a coolant is fed. In the casting die 4 the molten steel 2 is formed to a continuous casting 5 of square cross section, the outside of the casting 5 beginning to solidify due to the indirect cooling by the casting die 4.

The casting 5 emerges downwardly from the casting die 4 thereby entering a cooling section 6 wherein the casting 5 is cooled by being directly exposed to cooling water 7. The cooling section 6 serving for directly cooling the casting 5 consists of at least one row of flat jet nozzles 9 distantly surrounding the casting 5 and connected to one or more Water chambers 8. The flat jet nozzles 9 eject parallel flat jets extending continuously along the entire length of the cooling section 6 and by means of which the cooling water 7 is sprayed onto the casting 5 with a high kinetic energy. The flat jet nozzles 9 are inclined with respect to the casting 5 in such a manner that by virtue of a spray angle of about 90, measured in the vertical, they are able to cool the casting 5 Within the cooling section 6 by means of the cooling Water 7 over its entire length.

At the lower end of the cooling section 6 the casting 5 is supported on all sides by roller guide means which in the preferred embodiment are embodied in the form of guide rollers 10. These guide rollers 10 are rotatably mounted in holding devices 11. The casting die 4, the water chambers 8 with the flat jet nozzles 9 and the holding devices 11 with their associated guide rollers 10 are assembled detachably from each other to form an independent unit.

FIG. 2 shows the spatial arrangement of the individual parts. For the sake of simplifying the drawing only two holding devices 11 are shown, whereas the other holding devices 11 have been omitted. Moreover, the casting die 4 is shown in longitudinal section so that cooling pipes 12 incorporated therein are visible.

FIG. 3 illustrates the disposition of the flat jet nozzles 9 equidistantly surrounding the casting 5 on all sides. The water chambers 8 are about annularly disposed and receive the cooling water via admission pipes which are not shown. The cross sections of flow of said admission pipes, of the water chambers 8 and of the flat jet nozzles 9 are so conformed to each other that the cooling water 7 is constantly sprayed onto the casting 5 with high kinetic energy, e.g. 15 kg. m./min. cm.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed is:

1. In an apparatus for continuous casting of metal ingots, in combination, a casting die defining a cavity having an inlet end adapted to receive a stream of molten metal, and an outlet end downstream of said inlet end; indirect cooling means for cooling said die to at least partially solidify the molten metal in said cavity so that such metal issues from said outlet end in form of an elongated continuous ingot having an exposed circumferential surface and moving downstream from said outlet end in a predetermined path through and beyond an unobstructed cooling zone of substantial axial length; and direct cooling means surrounding said path in said cooling zone for directing against said ingot a plurality of narrow jets of cooling liquid having in direction longitudinally of said ingot a length corresponding to said substantial axial length, and in direction circumferentially of said ingot a width which is a fraction of said length, said jets impinging upon said surface with a kinetic energy of at least about 5 kp. m./unin. cm. over said substantial axial length of said zone and in side-by-side relationship but without overlap circumferentially of said ingot so as to provide continuous and substantially uniform coverage of said ingot in circumferential direction without overlap of said cooling liquid.

2. In an apparatus as defined in claim 1; and further comprising roller guide means engaging said surface of said ingot only downstream of said cooling zone.

3. In an apparatus as defined in claim 1, said jet nozzle means being constructed and arranged for directing against said ingot respective jets of cooling liquid whose kinetic energy of impingement upon said surface decreases gradually in direction downstream of said path.

4. In an apparatus as defined in claim 1, said jet nozzle means comprising jet nozzles having slot-shaped outlet openings elongated in at least substantial parallelism with the axial length of said cooling zone.

5. In an apparatus as defined in claim 1, said jet nozzle means comprising polydirectional jet nozzles.

6. In an apparatus as defined in claim 1; further comprising conduit means communicating with said jet nozzle means for supplying said cooling liquid thereto.

7. 'In an apparatus as defined in claim 6; and further comprising roller guide means engaging said surface of said ingot only downstream of said cooling zone.

8. In an apparatus as defined in claim 7, wherein said jet nozzle means, said conduit means and said roller guide means are detachably connected with said die and constitute with the same unit.

9. In an apparatus as defined in claim 1, said cavity having from said inlet end to said outlet end a longitudinal dimension which is at least substantially equal to said axial length of said cooling zone.

10. In an apparatus as defined in claim 9, wherein said cavity is of at least substantially circular cross-section; and wherein said longitudinal dimension is at least substantially equal to double the diameter of said cavity.

11. In an apparatus as defined in claim 9, wherein said cavity is of polygonal cross-section having a pre determined edge length; and wherein said longitudinal dimension is at least substantially equal to double said edge length.

References Cited UNITED STATES PATENTS 2,079,644 5/1937 Williams a- 164-89 2,747,245 5/1956 Junghans 164-282X 2,770,021 11/1956 Harter, Jr. et al. 164282X 3,066,364 12/1962 Baier 16482 3,381,741 5/1968 Gardner 16482X I. SPENCER OVERHOLSER, Primary Examiner R. S. ANNEAR, Assistant Examiner U.S. Cl. X.R. 16489 

